32,950
edits
No edit summary |
No edit summary |
||
(8 intermediate revisions by 3 users not shown) | |||
Line 1: | Line 1: | ||
{{Plugin Sidebar | {{Plugin Sidebar | ||
| manufacturer=Tektronix | |||
summary = Differential amplifier | | | series=560-series scopes | ||
image=Tek 2a61 front.jpg| | | type= 2A61 | ||
caption= | | summary = Differential amplifier plug-in | ||
| image=Tek 2a61 front.jpg | |||
introduced=1963 | | | caption=Tektronix 2A61 Front | ||
discontinued=(?) | | | designers=Larry Mayhew | ||
manuals= | | introduced=1963 | ||
* [ | | discontinued=(?) | ||
| manuals= | |||
* [[Media:2a61 1000-1 cal input adapter.pdf|Tektronix 2A61 1000:1 Cal Div/Input Adapter ( | * [[Media:070-0328-01.pdf|Tektronix 2A61 Manual]] (OCR) | ||
* [[Media:2a61 1000-1 cal input adapter.pdf|Tektronix 2A61 1000:1 Cal Div/Input Adapter (OCR)]] | |||
}} | }} | ||
The '''Tektronix 2A61''' is a differential amplifier plug-in for [[560-series scopes]] | The '''Tektronix 2A61''' is a high gain differential AC amplifier plug-in for the [[560-series scopes | 560 series oscilloscopes]], [[introduced in 1963]]. It has independently switchable low frequency and high frequency limits. The low frequency limit can go well below 1 Hz, but it can't go to DC. | ||
{{BeginSpecs}} | |||
{{Spec | Input impedance | 1 MΩ // ~100 pF }} | |||
{{Spec | Deflection | 10 μV/div to 20 mV/div in 1−2−5 sequence }} | |||
{{Spec | Bandwidth | Switch selectable:<br>Low Limit: ~0.06 to ~600 Hz<br>High Limit: ~60 Hz to ~0.3 MHz }} | |||
{{Spec | CMRR | 50,000:1 at Frequencies below 10 kHz }} | |||
{{Spec | Common Mode Range | -5 V to 5 V in A-B mode}} | |||
{{Spec | Input DC Bias | Max: ±0.1 V differential }} | |||
{{Spec | Line Filter | Switchable: at Least 50:1 attenuation }} | |||
{{EndSpecs}} | |||
==Internals== | ==Internals== | ||
The front end consists of a differential amplifier. | The front end consists of a differential amplifier. | ||
Up to serial number 986, the front-end differential amplifier | Up to serial number 986, the front-end differential amplifier used a pair of [[5842]] tubes biased with a tail current of 10 mA and a plate-to-cathode voltage of about 100 V. | ||
used a pair of [[5842]] tubes biased with a tail current of 10 mA and a | |||
plate-to-cathode voltage of about 100 V. | |||
[[File:2a61 frontend.png|thumb|left|upright|[[Nuvistor]]-based front-end amplifier]] | [[File:2a61 frontend.png|thumb|left|upright|[[Nuvistor]]-based front-end amplifier]] | ||
Starting with serial number 987, the front-end differential amplifier | Starting with serial number 987, the front-end differential amplifier was made with four [[7586]] [[nuvistor]] triodes: V424, V425, V524, and V525. | ||
was made with four [[7586]] [[nuvistor]] triodes: V424, V425, V524, and V525. | |||
The parallel combination of V424 and V425 forms one side of the differential amplifier | The parallel combination of V424 and V425 forms one side of the differential amplifier and the parallel combination of V524 and V525 forms the other side. | ||
and the parallel combination of V524 and V525 forms the other side. | However, for purposes of thermal stability, V424 is thermally connected to V524 and V425 is thermally connected to V525. | ||
However, for purposes of thermal stability, V424 is thermally connected to V524 | The tail current in the 987-and-up version is about 16 mA and the nuvistors have a plate-to-cathode voltage of about 70 V. | ||
and V425 is thermally connected to V525. | |||
The tail current in the 987-and-up version is about 16 mA | |||
and the nuvistors have a plate-to-cathode voltage of about 70 V. | |||
The second gain stage is a differential amplifier made of a pair of a pair of germanium PNP transistors. | The second gain stage is a differential amplifier made of a pair of a pair of germanium PNP transistors. | ||
To implement the low-frequency cutoff, | To implement the low-frequency cutoff, the 2A61 has a large electrolytic capacitor, C437 (13,000 μF or 20,000 μF depending on serial number), | ||
the 2A61 has a large electrolytic capacitor, | in the emitter frequency compensation network of the second differential amplifier stage. | ||
C437 (13,000 μF or 20,000 μF depending on serial number), | |||
in the emitter frequency compensation network | |||
of the second differential amplifier stage. | |||
Although C437 is polarized, it is operated with no DC bias | Although C437 is polarized, it is operated with no DC bias and therefore sees reverse voltage as part of normal operation. | ||
and therefore sees reverse voltage as part of normal operation. | D437 and D438 shunt C437, preventing it from ever seeing a voltage more than one diode drop. | ||
D437 and D438 shunt C437, preventing it from ever seeing a voltage | Most electrolytic capacitors are specified to handle reverse voltages of at least 1 V without damage. | ||
more than one diode drop. Most electrolytic capacitors are specified | |||
to handle reverse voltages of at least 1 V without damage. | |||
The 2A61 manual's calibration instructions recommend using the Heathkit IG-72 | The 2A61 manual's calibration instructions recommend using the Heathkit IG-72 Audio Generator. | ||
Audio Generator. | |||
A suitable input connector for the 2A61 is PC06 8- | A suitable input connector for the 2A61 is a PC06 8-4P / MS3106 8-4P. | ||
The standard cable for connecting the input signal to the 2A61 is the [[012-072]]. | |||
==Pictures== | ==Pictures== | ||
<gallery> | <gallery> | ||
Tek 2a61 front.jpg|Front | Tek 2a61 front.jpg | Front | ||
Tek 2a61 left.jpg|Left | Tek 2a61 left.jpg | Left | ||
Tek 2a61 right.jpg|Right | Tek 2a61 right.jpg | Right | ||
Tek 2a61 top.jpg|Top | Tek 2a61 top.jpg | Top | ||
Tek 2a61 bottom.jpg|Bottom | Tek 2a61 bottom.jpg | Bottom | ||
Tek 2a61 1.jpg | Tek 2a61 1.jpg | ||
Tek 2a61 2.jpg | Tek 2a61 2.jpg | ||
Tek 2a61 3.jpg | Tek 2a61 3.jpg | ||
Tek 2a61 4.jpg | Tek 2a61 4.jpg | ||
Tek-2a61 early.png|Schematic (early version) | Tek-2a61 early.png | Schematic (early version) | ||
Tek-2a61 late.png|Schematic (late version) | Tek-2a61 late.png | Schematic (late version) | ||
</gallery> | </gallery> | ||
[[Category:560 series plugins]] | [[Category:560 series plugins]] |